(a) State five effects. of each of the following practices on crop production: (1) irrigation; (ii) drainage. (b) List four methods of surface irrigation. (...

(a)(i) Five effects of irrigation on crop production

• It supplies water to crops during the dry season, allowing all-year-round cultivation.
• It increases crop yield by ensuring adequate moisture for growth.
• It dissolves soil nutrients and makes them available to plant roots.
• It aids seed germination and establishment of seedlings.
• It reduces the risk of crop failure caused by drought.
• (Negative) Excess or poor irrigation can cause waterlogging, leaching of nutrients and salinity/salt build-up.

(a)(ii) Five effects of drainage on crop production

• It removes excess water from the soil and prevents waterlogging.
• It improves soil aeration, giving roots enough oxygen for respiration.
• It warms the soil, promoting seed germination and root growth.
• It improves soil structure and workability for cultivation.
• It reduces the incidence of soil-borne diseases associated with wet soils.
• (Negative) Over-drainage can dry out the soil and remove needed moisture and nutrients.

(b) Four methods of surface irrigation

1. Basin/flooding irrigation.
2. Furrow irrigation.
3. Border (border-strip) irrigation.
4. Wild flooding / check-basin irrigation.

(c) Two main reasons why surface drainage is often necessary

• To remove excess rain or flood water from the surface and prevent waterlogging of crops.
• To improve soil aeration and workability so that crop roots and farm operations are not hindered.